DE102022121313A1 - Calibration standard and method for calibrating a form measuring machine - Google Patents

Abstract

A calibration standard includes an outer peripheral part having a columnar outer peripheral surface, a recess part recessed with a predetermined recess size from the columnar outer peripheral surface, and a gently curved surface part connecting the outer peripheral part and the recess part and a curved shape protruding to the outside of the calibration standard, having. A method of calibrating a form measuring machine includes: emitting measurement light from a probe of the form measuring machine to the calibration standard and detecting reflected light from the calibration standard using the probe; and performing magnification calibration based on the reflected light detection result and the outside diameter and the notch size of the calibration standard.

Description

BACKGROUND OF THE INVENTION

field of invention

The present invention relates to a calibration standard and a method for calibrating a form measuring machine, and more particularly to a calibration standard for use in calibrating a form measuring machine that measures a shape of a workpiece and a method for calibrating the form measuring machine.

State of the art

There are known shape measuring machines that measure a shape (such as roundness) of a workpiece by rotating a probe and the workpiece relative to each other about a rotation axis. For example, Japanese Patent Application Laid-Open No. 2010-014656 (Patent Literature 1) proposes a technique of measuring the shape of an inner surface of a center hole of a cylindrical workpiece mounted on a rotary disk and the shape of a lateral surface of the workpiece in a non-contact manner.

Patent Literature 1: Japanese Patent Application Laid-Open No. 2010-014656

SUMMARY OF THE INVENTION

The form measuring machine described above must perform a process called magnification calibration, which involves measuring a form of a calibration standard using a probe equipped with a non-contact optical sensor and associating an output signal from the probe with an actual calibrated displacement quantity (see, for example the Japanese industrial standard JIS B7451:1997 , Appendix 2).

13 Fig. 12 is a plan view (top view) for describing magnification calibration using a calibration standard (Flick standard or Flick master; hereinafter referred to as a master element).

As in 13 1, a master element M0 has a columnar shape, and a planar part (hereinafter referred to as a D recess part D0) is formed on a part of the lateral surface of the master element M0. In the following description, a two-dimensional polar coordinate system with a center C0 (central axis of the column) of the columnar master element M0 as an origin and a perpendicular line (hereinafter referred to as center line Lx) extending from the center C0 of the master element M0 to the D recess part D0 and is perpendicular to the planar D-recess part D0 as an X-axis. Here, the outer diameter (radius) R of the master element M0 and the recess size d of the D recess part D0 (a maximum distance between an extending line (dotted line) of the periphery of the master element M0 and the D recess part D0) are known. An angle θ d formed between a straight line extending from the center C0 of the master element M0 to an end part D0 _E of the D recess part D0 and a center line _Lx is also known because the angle θ _d depends on the recess size d.

As in 13 1, when performing magnification calibration, the optical sensor provided at a far end of the probe 30 emits a measurement light B1 to the surface of the master element M0 and detects the reflected light B2 returning from the surface of the master element M0. The magnification calibration is performed using the detection result of the reflected light B2 and the known parameters R and d. In this way, the shape measuring machine can perform precise measurement of the shape and dimensions of a measurement target.

In 13 θ indicates an angle of the measurement light B1 with respect to the center line Lx, R(θ) indicates a distance between the center C0 of the master element M0 and an incident position P0 of the measurement light B1, and φ(θ) indicates an angle (incident angle) of the measurement light B1 with respect to a normal direction (N0) to the surface of the master element M0 at the incident position P0 of the measurement light B1. In this case, the incident angle φ(θ) is expressed by the following expression (1).

Because the master element M0 is line-symmetrical with respect to the X-axis, only the upper side of the X-axis (0° ≤ θ < 180°) will be described below, and a description of the lower side of the X-axis (180° ≤ θ < 360°). $$\mathrm{\phi }\left(\mathrm{\theta }\right)=\{\begin{array}{cc}\mathrm{\theta },& \left(\text{if}\mathrm{\theta }<{\mathrm{\theta }}_{\text{i.e}}\right)\\ \mathrm{0,}& \left(\text{if}\mathrm{\theta }\ge {\mathrm{\theta }}_{\text{i.e}}\right)\end{array}$$

As indicated in the expression (1), in the case of θ≧θ _d , that is, when the measurement light B1 is incident on the lateral surface of the pillar, θ=0 is obtained. On the other hand, in the case of θ<θ _d , that is, when the measurement light B1 is incident on the D notch portion D0, the incident angle φ(θ) changes.

At this time, in order to correctly measure the shape of the master element M0, it is necessary to ensure a sufficient light quantity of the reflected light B2. Therefore, a smaller angle of incidence φ(θ) is preferable. For example, when the f-number of the optical sensor of the probe 30 is NA, it is preferable to set φ(θ) ≤ arcsin (NA).

When the incident angle φ(θ) is larger, among the components of the reflected light B2 reflected or scattered by the D notch portion D0, a component returning toward the optical sensor direction of the probe 30 is reduced. This means that the amount of light of the reflected light B2 that can be used for measuring the shape of the master element M0 is reduced. In particular, the incident angle φ(θ) increases at and near the end portion D0 _E of the D notch portion D0, and the amount of light of the reflected light B2 that can be used for measuring the shape decreases more. Therefore, particularly at and in the vicinity of the end part D0 _E of the D notch part D0, noise data is likely to be generated due to a reduction in the light quantity of the reflected light B2. When the detection result of the master element M0 contains such noise data, an error occurs in the gap size d of the master element M0, making it difficult to perform high-precision magnification calibration.

14 Fig. 12 is a graph of the incident angle φ(θ) (see expression (1)) where the radius R of the master element M0 is 12.5 mm, the recess size d is 20 µm, and the f-number NA of the probe is 0.05 ( permissible angle (= arcsin (NA)) ≈ 3°).

As in 14 1, at or near the end portion D0 _E of the D notch portion D0, the incident angle φ(θ) exceeds the allowable range (≈ 3°). Therefore, the amount of light of the reflected light B2 that can be detected by the optical sensor of the probe 30 decreases, thereby hindering high-precision magnification calibration.

The invention is in view of the above circumstances, and an object of the invention is to provide a calibration standard capable of performing high-precision calibration (magnification calibration) of a form measuring machine and a method of calibrating the form measuring machine.

In order to achieve the above object, according to a first aspect of the present invention, there is provided a calibration standard for use in calibrating a form measuring machine. The calibration standard includes: an outer peripheral part having a columnar outer peripheral surface; a recess portion recessed with a predetermined recess size from the columnar outer peripheral surface; and a gently curved surface part connecting the outer peripheral part and the recess part and having a curved surface shape protruding to outside of the calibration standard.

A second aspect of the present invention relates to the calibration standard according to the first aspect, wherein the recess part is formed with a planar shape on part of the columnar outer peripheral surface and the gently curved part is a shape along a circle inscribed in the columnar outer peripheral surface and the planar-shaped recess part is, has.

A third aspect of the present invention relates to the calibration standard according to the first aspect, wherein the recess part is formed on a part of the columnar outer peripheral surface in such a way that it has a linear shape parallel to a central axis of the calibration standard, and the gently curved surface part has a curved surface shape, which is shaped in such a way that the distance from a center of the calibration standard varies linearly with respect to an angle of a perpendicular line extending from the center of the calibration standard to the recess part.

A fourth aspect of the present invention relates to the calibration standard according to the first aspect, wherein the recess part is formed in a planar shape on a part of the columnar outer peripheral surface and the gently curved surface part has a curved surface shape shaped such that a distance from a center of the calibration standard varies linearly with respect to an angle of a perpendicular line extending from the center of the calibration standard to the recess part.

A method of calibrating a form measuring machine according to a fifth aspect of the present invention includes: emitting a measurement light from a probe of a form measuring machine to the calibration standard according to any one of the first to fourth aspects and detecting a reflected light from the calibration standard using the probe; and performing magnification calibration based on the reflected light detection result and an outer diameter and a notch size of the calibration standard.

According to the present invention, the provision of the gently curved surface part on the lateral surface of the columnar calibration standard can ensure the light amount of the reflected light during the measurement of the recess part, and thus allows high-precision magnification calibration.

character list

• 1 Fig. 14 is a front view of a form measuring machine.
• 2 Fig. 12 is a block diagram showing a control system of the form measuring machine.
• 3 12 is a top view (top view) of a calibration standard (flick standard or flick master) according to a first embodiment of the present invention.
• 4 12 is a top view (top view) of the calibration standard (Flick-Standard or Flick-Master) according to the first embodiment of the present invention.
• 5 12 is a partially enlarged plan view showing a smooth curve according to the first embodiment of the present invention.
• 6 14 is a graph showing an example of the calculation result for the angle of incidence φ(θ) in the calibration standard according to the first embodiment of the present invention.
• 7 Fig. 14 is a graph showing examples of the calculation result for the angle of incidence φ(θ) where the length of a D notch part varies.
• 8th 12 is a top view (top view) of a calibration standard (flick standard or flick master) according to a second embodiment of the present invention.
• 9 12 is a partially enlarged plan view showing a smooth curve according to the second embodiment of the present invention.
• 10 14 is a graph showing an example of the calculation result for the angle of incidence φ(θ) in the calibration standard according to the second embodiment of the present invention.
• 11 12 is a top view (top view) of a calibration standard (flick standard or flick master) according to a third embodiment of the present invention.
• 12 14 is a graph showing an example of the calculation result for the angle of incidence φ(θ) in the calibration standard according to the third embodiment of the present invention.
• 13 Fig. 12 is a plan view (top view) for describing magnification calibration using a calibration standard (Flick-Standard or Flick-Master).
• 14 14 is a graph showing a relationship between an angle θ of a measurement light relative to an X-axis and an incident angle φ of the measurement light incident on a surface of the calibration standard.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following, embodiments of a calibration standard and a method for calibrating a form measuring machine according to the present invention will be described based on the accompanying drawings.

[First embodiment]

(form measuring machine)

First, the configuration of a form measuring machine is schematically described with reference to FIG 1 and 2 described. 1 Fig. 12 is a front view of the form measuring machine.

In the 1 The shape measuring machine 10 shown can measure an outer shape of a cylindrical workpiece W and a shape (such as roundness) of an inner surface of a narrow hole H in the workpiece W. in the in 1 In the example shown, the narrow hole H is a through hole formed along a central axis of the workpiece W. FIG. The inner diameter of the narrow hole H is very small (for example, the inner diameter is 500 µm or less). In 1 the XYZ directions are orthogonal to each other. The X direction is a horizontal direction, the Y direction is a horizontal direction orthogonal to the X direction, and the Z direction is a perpendicular (or vertical) direction.

As in 1 1, a form measuring machine 10 includes a body base 12, a stage rotating mechanism 14, a stage 18, a column 20, a carriage 22, an arm 24, a displacement detector 26, a detector drive mechanism 28, and a controller 50.

The stage rotating mechanism (high-precision rotating mechanism) 14 is a rotating mechanism for rotating the workpiece W around a rotation axis C. The stage rotating mechanism 14 precisely rotates the later-described stage 18 around a rotation axis C parallel to the Z direction. The stage rotating mechanism 14 includes a rotor 16 rotatably provided on the body base 12 . The stage 18 is held on the upper surface of the rotor 16. The stage rotation mechanism 14 includes a motor (not shown) that rotates the rotor 16 around the rotation axis C with high precision, and an encoder (not shown) that detects a rotation angle of the rotor 16 .

The workpiece W can be mounted on the stage 18. The stage 18 may hold and fix the workpiece W directly, or may hold and fix the workpiece W via a workpiece holder (not shown).

The stage 18 is held on a holding surface (upper surface) of the rotor 16 and is configured to rotate about the rotation axis C together with the rotor 16. In this way, the workpiece W held and fixed on the stage 18 can be rotated together with the stage 18 be rotated around the axis of rotation C. Note that the stage 18 and the rotor 16 are examples of the “stage rotating mechanism”.

The stage 18 includes a linear motion mechanism and a tilting mechanism (both not shown). The linear motion mechanism moves the stage 18 in the X-direction and in the Y-direction by driving the motor (not shown) to adjust the position of the stage 18 in an XY plane (horizontal plane) orthogonal to the rotation axis C. The tilt mechanism rotates the stage 18 in the X direction and in the Y direction by driving the motor (not shown) to adjust the tilt angle of the stage 18 with respect to the XY plane.

On the body base 12, a pillar 20 extending parallel to the Z-direction is provided in a standing state. The pillar 20 has a lower end portion fixed to the upper surface of the body base 12 .

The carriage 22 is supported by the column 20 such that it can be moved in the Z direction. The carriage 22 is configured to be movable in the Z direction by driving a motor (not shown).

The arm 24 is held by the carriage 22 so that it can be moved in the XY directions. The arm 24 is configured to move in the horizontal direction (in the XY directions) can be moved respectively by the linear motion mechanism 70 and a vertex adjustment mechanism 72 (see 2 ). The linear motion mechanism 70 and the vertex adjustment mechanism 72 each include a drive source (motor, etc.) for moving the arm 24 in the horizontal direction.

The lateral faces of the arm 24 and the column 20 have scales provided along the X-direction and the Z-direction, respectively. The controller 50 can detect the position of the probe 30 in the XZ directions by reading the graduations of the scales using a sensor (not shown).

The displacement sensor 26 is supported by the arm 24 via the detector drive mechanisms 28. As shown in FIG. The displacement detector 26 includes the feeler 30 . The probe 30 detects the shape of the surface of the workpiece W (the outer surface or the inner surface of a hole H) in the workpiece W). The probe 30 is a non-contact type probe that can detect the surface shape of the workpiece W without touching the surface of the workpiece W in this embodiment.

No particular specification is made here as to the type of non-contact probe 30 as long as the probe can detect the surface shape without touching the surface of the workpiece W. For example, the non-contact probe may use any of various techniques such as laser interferometry, white interferometry, spectral domain optical coherence tomography (SD-OCT), or swept source optical coherence tomography (SS-OCT).

The detector driving mechanism 28 is arranged between the arm 24 and the displacement detector 26 . The detector drive mechanism 28 includes a linear motion mechanism and a tilting mechanism (both not shown). The linear motion mechanism moves the displacement detector 26 in the X-direction and the Y-direction by driving the motor (not shown) to adjust the position of the probe 30 in an XY plane (horizontal plane) orthogonal to the rotation axis C. The tilting mechanism rotates the displacement detector 26 in the X-direction and the Y-direction by driving the motor (not shown) to adjust the tilting angle of the sample 30 with respect to the XY plane. In this way, relative alignment (probe alignment) can be made between the probe 30 and the axis of rotation C by controlling the position and tilt angle of the probe 30 in the horizontal direction (X and Y directions) by the detector driving mechanism 28 (linear motion mechanism and tilting mechanism ) is set.

The detector drive mechanism 28 further includes a drive source (e.g., a motor, etc.) for rotating the probe 30 about a rotation axis (probe rotation axis) AX. The detector drive mechanism 28 is an example of the “probe rotating mechanism”.

2 Fig. 12 is a block diagram showing a control system of the form measuring machine.

The controller 50 controls the operation of each part of the shape measuring machine 10 (including a measuring operation of the surface shape of the workpiece W and a probe alignment operation described later). The controller 50 is implemented by a general purpose computer such as a PC or a microcomputer. The controller 50 includes a central processing unit (CPU), read only memory (ROM), random access memory (RAM), storage device (e.g., a hard disk drive (HDD) or a solid state drive (SSD), etc.) and an input/output interface. In the controller 50, various programs such as control programs stored in the storage device are loaded into the RAM. When the CPU executes the programs loaded in the RAM, the function of each part of the form measuring machine 10 is implemented, and various arithmetic processing or control processing is performed through the I/O interface.

The controller 50 includes an operation unit 52 (e.g., a keyboard and a mouse) that receives an operation input from a user, an operation user interface (UI), and a display 54 for displaying the detection results.

As in 2 As shown, the controller 50 includes a displacement calculator 56 and a drive controller 58.

The displacement calculator 56 calculates a displacement of the workpiece W based on the detection result of the displacement of the surface of the workpiece W detected by the displacement detector 26, and measures the shape of the surface of the workpiece W (for example, the outer shape of the workpiece W or the roundness of the hole H, etc .).

The drive controller 58 controls the linear motion mechanism 70, the vertex adjustment mechanism 72, the detector drive mechanism 28 and the stage rotating mechanism 14 to adjust the relative position of the workpiece W and the probe 30.

(Procedure for a magnification calibration)

A method for magnification calibration of the form measuring machine 10 is described below. 3 and 4 12 are plan (top) views of the calibration standard (Flick standard or Flick master, hereinafter referred to as master element) according to the first embodiment of the present invention.

In a magnification calibration of the form measuring machine 10, a master element M1 is first mounted on the stage 18 such that its center C1 (central axis of a column) is aligned with the axis of rotation C of the stage 18 (see FIG 3 and 4 ). Then, the shape of the master element M1 is measured by controlling the stage rotating mechanism 14, the detector drive mechanism 28 and the carriage 22 to move the probe 30 to emit the measuring light B1 to the master element M1 while the relative position of the workpiece W and the probe 30 is adjusted and causing the reflected light to be detected by the master element M1. Then, the magnification calibration is performed using the detection result of the reflected light from the master element M1 and a known outer diameter (radius) R and a notch size.

(calibration standard)

The master element M1 is described below.

As in 3 and 4 shown, the master element M1 according to this embodiment has a columnar shape, with a planar part (an example of the recess part, hereinafter referred to as D recess part D1) on a part of an outer peripheral part (an outer peripheral surface, a lateral surface) S1 of the master element M1 is formed by cutting a predetermined cut-out size d at the outer peripheral part. Between the columnar lateral surface S1 and the D notch part D1 of the master element M1, a curved lateral surface (a gently curved surface part, hereinafter referred to as a gentle curve) E1 is formed. The outer diameter (radius) R of the master member M1 and the recess size d of the D recess part D1 (the maximum distance between an extending line (dotted line) of the outer periphery of the master member M1 and the D recess part D1) are known. A Y-coordinate L _D of an end part _D1E of a virtual D-notch part D1 (part indicated by a broken line) when it is assumed that the smooth curve E1 does not exist is also known because the Y-coordinate L _D is different from the Recess size d depends.

In the following description, a two-dimensional polar coordinate system is used that takes the center C1 of the master element M1 (the central axis of the pillar) as an origin and a perpendicular line extending from the center C1 of the master element M1 to the D recess part D1 as an X Axis extends, has.

Because the master element M1 is line-symmetrical with respect to the X-axis, only the smooth curve E1 on the upper side of the X-axis (0°≦θ<180°) will be described below, and a description of the smooth curve E1 will be referred to the lower side of the X-axis (180° ≤ θ < 360°) is omitted.

As in 3 and 4 As shown, the smooth curve E1 is part of an inscribed circle IC1 inscribed on the lateral surface S1 and the D-notch part D1 of the master element M1. An inside contact point between the lateral surface S1 of the master element M1 and the inscribed circle IC1 is P1, and an inside contact point between the D recess part D1 and the inscribed circle IC1 is P2.

When the coordinates of the center C10 of the inscribed circle IC1 are (x ₀ , y ₀ ) and the radius is r, the inscribed circle IC1 is expressed by the following expression (2). $${\left(\text{x}-{\text{x}}_{\text{0}}\right)}^2+{\left(\text{y}-{\text{y}}_{\text{0}}\right)}^2={\text{right}}^2$$

$${\text{y}}_{\text{0}}=\text{L}$$

The radius r of the inscribed circle IC1 is expressed as follows using known variables. Since the inscribed circle IC1 is inscribed in the D recess part D1, the following expressions (3) and (4) can be obtained. $${\text{x}}_{\text{0}}=\left(\text{R}-\text{i.e}-\text{right}\right)$$

$${\text{<figure-callout id="0" label="y" filenames="DE102022121313A1\_0021.png,DE102022121313A1\_0022.png" state="{{state}}">y</figure-callout>}}_{\text{0}}=\text{L}$$

In the expression (4), L indicates a Y-coordinate of the inner contact point P2 where the inscribed circle IC1 is inscribed in the D recess part D1. L can be set optionally. For example, when L is set to half the length (L _D ) of the virtual D notch part D1 (part indicated by dashed lines), the effect of the smooth curve E1 can be obtained while ensuring a sufficient length of the D notch part D1.

Since the inscribed circle IC1 is inscribed on the lateral surface S1 of the master element M1, the following expression (5) can be obtained. $$\text{R}=\text{right}+\sqrt{{\text{x}}_0^2+{\text{<figure-callout id="0" label="y" filenames="DE102022121313A1\_0021.png,DE102022121313A1\_0022.png" state="{{state}}">y</figure-callout>}}_0^2}$$

When expression (5) for r is solved using expressions (3) and (4), the following expression (6) can be obtained. $$\text{right}=\text{R}-\left({\text{<figure-callout id="2" label="L" filenames="DE102022121313A1\_0024.png,DE102022121313A1\_0029.png" state="{{state}}">L</figure-callout>}}^{\text{2}}-{\text{i.e}}^{\text{2}}\right)/2\text{i.e}$$

Then, the distance R(θ) between the center C10 of the inscribed circle IC1 and a point on the smooth curve E1 is expressed with known variables as follows.

First, according to 3 and 4 the point (x, y) on the smooth curve E1 is expressed by (x, y) = (R(θ)cos θ), R(θ)sin θ). When these values are assigned to the expression (1) of the inscribed circle IC1, the following expression (7) can be obtained. $${\left(\text{R}\left(\mathrm{\theta }\right)\text{cos}\mathrm{\theta -}{\text{x}}_0\right)}^2+{\left(\text{R}\left(\mathrm{\theta }\right)\text{sin}\mathrm{\theta -}{\text{y}}_0\right)}^2={\text{right}}^{\text{2}}$$

When the expression (7) is converted, the following expression (8) can be obtained. $$\text{R}{\left(\mathrm{\theta }\right)}^2-2\left({\text{x}}_0\text{cos}\mathrm{\theta }+{\text{<figure-callout id="0" label="y" filenames="DE102022121313A1\_0021.png,DE102022121313A1\_0022.png" state="{{state}}">y</figure-callout>}}_{\text{0}}\text{cos}\mathrm{\theta }\right)\text{R}\left(\mathrm{\theta }\right)+\left({\text{x}}_{\text{0}}{}^{\text{2}}+{\text{<figure-callout id="0" label="y" filenames="DE102022121313A1\_0021.png,DE102022121313A1\_0022.png" state="{{state}}">y</figure-callout>}}_{\text{0}}{}^{\text{2}}-{\text{right}}^2\right)=0$$

When expression (8) is solved for R(θ), the following expression (9) can be obtained. $$\begin{array}{l}R\left(\theta \right)\left(x_{0}cOs\theta +y_{0}cOs\theta \right)\hfill \\ +\sqrt{{\left(x_{0}cOs\theta +y_{0}cOs\theta \right)}^2-x_0^2+{\mathrm{<figure-callout\; id="0"\; label="y"\; filenames="DE102022121313A1\_0021.png,DE102022121313A1\_0022.png"\; state="\{\{state\}\}">y</figure-callout>}}_0^2-{\mathrm{right}}^2}\hfill \end{array}$$

When r in expression (6) is assigned to expression (9), R(θ) can be calculated with only the known variables (R, d, L, x ₀ and yo) and θ.

Furthermore, there in 4 N1 indicates a normal line to the surface of the master element M1 at an incident position P0 of the incident light B1, and φ(θ) indicates an angle (incident angle) of the measurement light B1 with respect to the normal line N1. The angle of incidence φ(θ) is expressed using known variables as described below.

5 12 is a partially enlarged plan view showing the gentle curve E1.

As in 5 1, P0 is the incident position of the measurement light B1, and P3 is a point on the smooth curve E1 that is away from the incident position P0 by Δθ. if in 5 Δθ is sufficiently small (Δθ ≈ 0) R(θ) tan Δθ = R(θ)Δθ. In this case, the incident angle φ(θ) is expressed by the following expression (10). $$\mathrm{\phi }\left(\mathrm{\theta }\right)=\text{arctan}\left[\left\{\text{R}\left(\mathrm{\theta }+\mathrm{\Delta \theta }\right)-\text{R}\left(\mathrm{\theta }\right)\right\}/\left(\text{R}\left(\mathrm{\theta }\right)\mathrm{\Delta \theta }\right)\right]$$

(Example of the calculation result for the angle of incidence φ(θ))

6 14 is a graph showing an example of the calculation result for the angle of incidence φ(θ) in the master element M1 according to the first embodiment. The curve F1 in 6 shows the incident angle φ(θ), where the radius R of the master element M1 is 12.5 mm, the cutout size d is 20 µm, and the F-number NA of a measuring optical system of the probe 30 is 0.05 (allowable angle (= arcsin (NA)) ≈ 3°). In 6 is the Y-coordinate of a boundary (internal contact point P2) between the D notch part D1 and the smooth curve E1, that is, the length L corresponding to 1/2 the length of the D notch part D1, to half the length (L _D ) of the virtual D notch part D1 (part shown by broken line) (L = 1/2 L _D ).

As in 6 1, in this embodiment, at and near the boundary (inner contact part P2) between the D recess part D1 and the smooth curve E1, the incident angle φ(θ) is smaller than the allowable angle (≈3°). Therefore, a sufficient light amount of the reflected light that can be detected by the optical sensor of the probe 30 can be secured, and the shape of the master element M1 can be measured with high precision. Thus, high-precision magnification calibration can be performed.

In addition, in this embodiment, the smooth curve E1 of the master element M1 can be easily manufactured because it has a circular shape. And because there is no inflection point in the shape of the lateral face of a part of the gentle curve E1 of the master element M1, a measured waveform is stable and the shape of the master element M1 can be measured with a high precision.

According to this embodiment, the length (2L) of the D notch part D1 can be optionally adjusted so that an optimal geometry depending on the F number NA of the probe 30 can be used.

7 Fig. 12 is a graph showing examples of the calculation result for the angle of incidence φ(θ) where the length (2L) of the recess part D1 is varied. In the curve diagram of 7 the calculation parameters are those of 6 similarly, where the radius R of the master element M1 is 12.5 mm, the recess size d is 20 µm and the f-number NA of the optical measuring system of the probe 30 is 0.05 (allowable angle (= arcsin(NA)) ≈ 3 °).

In 7 the curves F1-1 to F1-3 indicate the calculation results for a length (2L) of the D notch part D1 of L=1/4L _D , L=1/2L _D and L=3/4L _D , respectively. In each of the curves F1 to F3, the incident angle φ(θ) is smaller than the allowable angle (≈3°).

The longer in 7 is the length (2L) of the D notch part D1, the larger the maximum value of the incident angle θ(θ) becomes. And conversely, the shorter the length (2L) of the D notch part D1 is, the smaller the maximum value becomes.

Therefore, in this embodiment, the length (2L) of the D notch part D1 corresponding to the F number NA of the probe 30 can be optimized. For example, as indicated by the curve F1-3, by increasing the length (2L) of the D notch portion D1, the D notch portion D1 (linear portion) can be lengthened. This allows the measured waveform to be stabilized. On the other hand, as indicated by the curve F1-1, shortening the length (2L) of the D notch part D1 reduces the maximum value of θ(θ). Therefore, high-precision measurement becomes possible even when the F-number NA of the sensor 30 is small.

[Second embodiment]

A second embodiment of the present invention will be described below. The second embodiment differs from the first embodiment in the shape of a master element M2. Since the form measuring machine 10 in the second embodiment and the configuration method thereof are similar to those in the first embodiment, a description thereof is omitted here.

(calibration standard)

8th Fig. 14 is a top view of a calibration standard (Flick standard or Flick master) according to a second embodiment of the present invention. In 8th FIG. 12 is an extension line (dotted line) of a columnar outer peripheral surface S2 of a master member M2 together with the D recess part D0 (dashed line) of FIG 13 shown.

As in 8th 1, the master element M2 according to this embodiment has a columnar shape, and a curved lateral surface (gentle curve) E2 is formed on a part of the outer peripheral part (the outer peripheral surface, the lateral surface) S2. Here, the distance (hereinafter referred to as the clearance size) d between a crossing point PI where the outer diameter (radius) R crosses the lateral surface E2 of the master element M2 on the X-axis and the extension line of the outer peripheral surface S2 is known.

As in 8th 1, in this embodiment, the recess part D2 is formed in a linear shape parallel to the central axis (C2) of the master element M2 at the position of the crossing point PI.

In the following description, a two-dimensional polar coordinate system is used that takes the center C2 of the master element M2 (the central axis of the column) as an origin and a line extending through the intersection point PI with the lateral face E2 of the master element M2 as the X- axis.

Because the master element M2 as in 8th shown is line symmetric with respect to the X-axis, only the upper side of the X-axis (0° ≤ θ < 180°) will be described and a description of the lower side of the X-axis (180° ≤ θ < 360° ) renounced.

On the master element M2, the distance R(θ) from the center C2 to the surface of the master element M2 is expressed by the following expression (11). As shown in the expression (11), the lateral surface S2 (θ ≥ θ ₀ ) has a columnar shape with a radius R, while the lateral surface E2 (θ < θ ₀ ) has a curved surface shape linear with respect to a Angle θ varies. Hereinafter, regarding the lateral surface E2 (θ<θ ₀ ), a portion above the X-axis is referred to as a linear variation curve E2(+), and a portion below the X-axis is referred to as a linear variation curve E2(-). $$R\left(\theta \right)=\{\begin{array}{rr}\hfill R-\left(1-\theta /{\theta }_0\right)\mathrm{i.e}& \hfill \left(\text{if}\theta <{\theta }_{\mathrm{i.e}}\right)\\ \hfill R,& \hfill \left(\text{if}\theta \ge {\theta }_{\mathrm{i.e}}\right)\end{array}$$

In the expression (11), the angle θ ₀ indicates an angle (alternating angle) of a point P5 that is a boundary between the columnar lateral surface S2 of the master element M2 and the linear variation curve E2(+).

9 12 is a partially enlarged plan view showing the linear variation curve E2(+).

As in 9 1, P0 is an incident position of the measurement light B1, and P6 is a point on the linear variation curve E2 that is away from the incident position P0 by Δθ. N2 indicates a normal line to the surface of the master element M2 at the incident position P0 of the measurement light B1, and φ(θ) indicates an angle (incident angle) of the measurement light B1 with respect to the normal line N2. if in 9 Δθ is sufficiently small, (Δθ = 0), R(θ) tan Δθ ≈ R(θ)Δθ is obtained. In this case, the incident angle φ(θ) is expressed by the following expression (12). $$\mathrm{\phi }\left(\mathrm{\theta }\right)=\text{arctan}\left[\left\{\text{R}\left(\mathrm{\theta }+\mathrm{\Delta \theta }\right)-\text{R}\left(\mathrm{\theta }\right)\right\}/\left(\text{R}\left(\mathrm{\theta }\right)\mathrm{\Delta \theta }\right)\right]$$

The expression (0≦θ<θ ₀ ) of the linear variation curve E2(+) in the expression (11) is assigned to the expression (12) to obtain the following expression (13). $$\mathrm{\phi }\left(\mathrm{\theta }\right)=\text{arctan}\left[\text{i.e}/\left\{\text{R}{\mathrm{\theta }}_0-\left({\mathrm{<figure-callout\; id="0"\; label="\theta "\; filenames="DE102022121313A1\_0021.png,DE102022121313A1\_0022.png"\; state="\{\{state\}\}">\theta </figure-callout>}}_0-\mathrm{\theta }\right)\text{i.e}\right\}\right]$$

From the expression (13), the following expression (14) is obtained. $$\mathrm{\phi }\left(\mathrm{\theta }\right)\approx \text{i.e}/\left(\text{R}{\mathrm{\theta }}_{\text{0}}\right)$$

According to expression (14), the angle of incidence φ(θ) is constant regardless of θ.

(Example of the calculation result for the angle of incidence φ(θ))

10 14 is a graph showing an example of the calculation result for the angle of incidence φ(θ) in the master element M2 according to the second embodiment. The curve F2 in 10 represents the angle of incidence φ(θ), where the radius R of the master element M2 is 12.5 mm, the gap size d is 20 µm, the f-number NA of the measuring optical system of the probe 30 is 0.05 (allowable angle (= arcsin(NA)) ≈ 3°) and the alternating angle θ ₀ is equal to 10°.

As in 10 , in this embodiment, at and near a boundary (a point P5) between the columnar lateral surface S2 of the master element M2 and the linear variation curve E2, the incident angle φ(θ) is smaller than the allowable angle (≈3°). Therefore, a sufficient amount of light of the reflected light that can be detected by the optical sensor of the probe 30 can be secured, and the shape of the master element M2 can be measured with high precision. Thus, high-precision magnification calibration can be performed.

Furthermore, in this embodiment, as shown in expression (14), the incident angle φ(θ) of the measurement light B1 is substantially constant regardless of θ. Therefore, the reflection angle of the measurement light B1 can be made constant and small. Therefore, measurement can be performed with high and uniform quality.

[Third Embodiment]

A third embodiment of the present invention will be described below. The third embodiment differs from the first and second embodiments in the shape of the master element M3. Because the form measuring machine 10 in the third embodiment and the configuration method thereof are similar to those in the first embodiment, a description thereof is omitted here.

(calibration standard)

11 12 is a top view (top view) of the calibration standard (Flick-Standard or Flick-Master) according to the third embodiment of the present invention. In 11 FIG. 12 is an extension line (dotted line) of a columnar outer peripheral surface S3 of the master member M3 together with the D recess part D0 (dashed line) of FIG 13 shown.

As in 11 As shown, the master element M3 according to this embodiment has a columnar shape, with a planar part (an example of the recess part, hereinafter referred to as D recess part D3) being formed on a part of the outer peripheral part (the outer peripheral surface, the lateral surface) S3 . A curved lateral surface (a gentle curve, hereinafter referred to as a linear variation curve) E3 is formed between the columnar lateral surface S3 and the D notch part D3 of the master element M3. Here, the distance (hereinafter referred to as clearance size) d between a crossing point P9 where the outer diameter (radius) R crosses the lateral surface E3 of the master element M3 on the X-axis and the extension line of the outer peripheral surface S3 is known.

In the following description, a two-dimensional polar coordinate system is used that takes the center C3 of the master element M3 (the central axis of the pillar) as an origin and a perpendicular line extending from the center C3 of the master element M3 to the D recess part D3 as a Having X-axis.

Because the master element M3 as in 11 shown is line symmetric with respect to the X-axis, only the upper side of the X-axis (0° ≤ θ < 180°) will be described and a description of the lower side of the X-axis (180° ≤ θ < 360° ) renounced.

On the master element M3, a distance R(θ) from the center C3 to the surface of the master element M3 is expressed by the following expression (15). As shown in the expression (15), the late ral surface S3 (θ ≥ θ ₀ ) has a columnar shape with a radius R, while the D recess part D3 (θ < θ ₁ ) has a planar shape. A lateral face E3 (θ ₁ ≤ θ < θ ₀ ) between the columnar lateral face S3 and the D recess part D3 of the master member M3 has a curved shape that varies linearly with respect to the angle θ. Hereinafter, in the lateral surface E3 (θ ₁ ≤ θ < θ ₀ ), a part above the X-axis is referred to as a linear variation curve E3(+), and a part below the X-axis is referred to as a linear variation curve E3(-) designated. $$R\left(\theta \right)=\{\begin{array}{rr}\hfill \left(R-\mathrm{i.e}\right)R/\text{cos}\theta & \hfill \left(\text{if}\theta <{\theta }_1\right)\\ \hfill R-\left(1-\theta /{\theta }_0\right)\mathrm{i.e},& \hfill \left(\text{if}{\mathrm{<figure-callout\; id="1"\; label="\theta "\; filenames="DE102022121313A1\_0020.png,DE102022121313A1\_0021.png"\; state="\{\{state\}\}">\theta </figure-callout>}}_1\le \theta <{\theta }_0\right)\\ \hfill R,& \hfill \left(\text{if}\theta \ge {\theta }_0\right)\end{array}$$

In the expression (15), the angle θ ₀ represents an angle (alternating angle) of a point P7 that is a boundary between the columnar lateral surface S3 and the linear variation curve E3(+) of the master element M3, and the angle θ ₁ represents one angle (alternating angle) of a point P8 which is a boundary between the linear variation curve E3(+) and the D notch part D3.

Here, θ ₁ is a non-zero angle that satisfies the condition of the following expression (16). $$\left(\text{R}-\text{i.e}\right)/\text{cos}{\mathrm{\theta }}_1=\text{R}-\left(1-{\mathrm{<figure-callout\; id="1"\; label="\theta "\; filenames="DE102022121313A1\_0020.png,DE102022121313A1\_0021.png"\; state="\{\{state\}\}">\theta </figure-callout>}}_1/{\mathrm{\theta }}_0\right)\text{i.e}$$

When the expression (16) is approximately solved, the following expression (17) is obtained. $${\mathrm{<figure-callout\; id="1"\; label="\theta "\; filenames="DE102022121313A1\_0020.png,DE102022121313A1\_0021.png"\; state="\{\{state\}\}">\theta </figure-callout>}}_1=\text{2d}/\left(\text{R}-\text{i.e}\right){\mathrm{<figure-callout\; id="0"\; label="\theta "\; filenames="DE102022121313A1\_0021.png,DE102022121313A1\_0022.png"\; state="\{\{state\}\}">\theta </figure-callout>}}_0$$

(Example of the calculation result for the angle of incidence φ(θ))

12 14 is a graph showing an example of a calculation result for the angle of incidence φ(θ) in the master element M3 according to the third embodiment. 12 also shows the curve F1-2 (see 7 ) according to the first embodiment for comparison.

The curve F3 in 12 shows the incident angle φ(θ), where the radius R of the master element M3 is 12.5 mm, the cutout size d is 20 µm, the f-number NA of the measuring optical system of the probe 30 is 0.05 (allowable angle (= arcsin (NA)) ≈ 3°), the alternating angle θ ₀ is 6.3°, and the length (2L) of the D notch part D3 is L=1/2 L _D .

As in 13 1, in this embodiment, the incident angle φ(θ) is increased in the D notch part D3. On the other hand, in the region of the linear variation curve E3, the angle of incidence φ(θ) immediately assumes a small constant value. Therefore, in this embodiment, an angle range with a large incident angle φ(θ) in which the measurement quality tends to deteriorate can be reduced, and the measurement quality of the magnification calibration can be improved.

[Modification]

In the above-described embodiments, a part of a circle (E1) or the linear variation curve (E2 and E3) is used as an example of the smooth curve. However, the smooth curve is not limited to these examples. For example, well-known shapes such as a clothoid or a function of the nth order (where n is a natural number greater than or equal to 2; for example, a cubic curve) or a protruding curve outside the master elements M1 to M3 can also be used. In addition, one or more lines can form a pseudo-smooth curve.

In the above-described embodiments, an example has been described in which a D recess part D1, a recess part D2, and a D recess part D3 are formed on the lateral surfaces of the master elements M1 to M3, respectively. However, two or more D recess parts D1, two or more recess parts D2 and/or two or more D recess parts D3 can also be formed.

Reference List

10

form measuring machine;

12

body base;

14

stage rotating mechanism;

16

Rotor;

18

Stage;

20

Pillar;

22

Sleds;

24

Poor;

26

displacement detector;

28

detector drive mechanism;

30

Sensor;

32

Camera;

34

camera clamp;

50

control device;

52

operating unit;

54

Advertisement;

56

displacement calculator;

58

drive control device;

60

image pickup controller;

70

linear motion mechanism;

72

crown adjustment mechanism;

M1 to M3

Calibration standard (Flick-Standard or Flick-Master).

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• JP 2010014656 [0002, 0003]

Non-patent Literature Cited

• JIS B7451:1997 [0004]

Claims (5)

A calibration standard for use in calibrating a form measuring machine, comprising: an outer peripheral part having a columnar outer peripheral surface, a recess part recessed with a predetermined recess size from the columnar outer peripheral surface, and a smoothly curved surface part connecting the outer peripheral part and the recess part and having a curved shape protruding to outside of the calibration standard. calibration standard claim 1 wherein: the recess part is formed in a planar shape on part of the columnar outer peripheral surface, and the gently curved surface part has a shape along a circle inscribed in the columnar outer peripheral surface and the planar-shaped recess part. calibration standard claim 1 , wherein: the recess part is formed at a part of the columnar outer peripheral surface in a linear shape parallel to a center axis of the calibration standard, and the gently curved surface part has a curved surface shape shaped such that the distance from a center of the Calibration standards varies linearly with respect to an angle of a perpendicular line extending from the center of the calibration standard to the recess part. calibration standard claim 1 , wherein: the recess part is formed in a planar shape on part of the columnar outer peripheral surface, and the gently curved surface part has a curved surface shape shaped such that the distance from a center of the calibration standard is linear with respect to an angle of a vertical line , which extends from the center of the calibration standard to the recess part, varies. A method of calibrating a form measuring machine, comprising: emitting a measuring light from a probe of a form measuring machine to the calibration standard according to any one of Claims 1 until 4 and detecting a reflected light from the calibration standard using the probe, and performing magnification calibration based on a detection result of the reflected light and the outside diameter and the notch size of the calibration standard.

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